


the haunting

by TheDragonLover



Series: Tumblr Requests [6]
Category: Undertale (Video Game)
Genre: Fellswap Papyrus - Freeform, Gen, fellswap sans - Freeform, not fontcest, swapfell red, talking through dreams, there's a spooky thing in our house and it needs to cut it out, they become friends eventually, written for request
Language: English
Status: Completed
Published: 2018-09-02
Updated: 2018-09-02
Packaged: 2019-07-07 19:26:02
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,976
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15914724
Author URL: https://archiveofourown.org/users/TheDragonLover/pseuds/TheDragonLover
Summary: Something is messing with their kitchen, and Sans is going to lose it.---For a request to write for FellSwap (SwapFell Red), with a prompt.





	1. Chapter 1

The first time all of the kitchen cabinets were left open, Sans blamed his brother, because of course Papyrus would leave things a mess. He gave a bit of a lecture and made him promise not to do it again, before stomping back into the kitchen to continue his masterpiece of a meal. And Papyrus let him do it, not willing to point out that he hadn’t been in the kitchen all day. If it made Sans feel better to let out some steam with some yelling, all right, whatever. The second time he was a bit annoyed by it, but again, it was all right, really.

The third time, the contents of the cabinet were also rearranged, and Sans (finally) came to the conclusion that it wasn’t his brother, because even  _he_  knew how to follow instructions he’s heard more than once. He didn’t apologize for yelling, at least not verbally. Instead, he collaborated with him to see how they could figure out the issue.

Examining hinges closely and tightening any screws, Sans had expected the problem to be solved. He wasn’t a carpenter, but he knew how to read a manual to the letter. Then the next day he walked in to find all of the pasta on the ground—Papyrus, of course, with his hands up defensively, wordlessly claiming innocence—and  _that_  was the last straw. He set up cameras all around the kitchen, determined to find the culprit.

They were all dead by morning, the footage corrupt, and now the pasta  _and_  the cereal were on the ground. Papyrus could hear his brother’s teeth grinding from across the room, and winced. Oh, boy.

Next was the stakeout. Papyrus wasn’t fond of the idea, but he went along with it because, well, he wasn’t going to refuse his brother when he had that look in his sockets. Armed with bones and metal ladles, they sat in opposite corners of the kitchen for maximum coverage. Any time Papyrus threatened to doze off, Sans banged a pot to jolt him awake. It was a long night, where neither of them made any progress.

Then, the moment that Sans stomped out of the kitchen to grab the mail and left his dozing brother, the pot came flying across the room to smack Papyrus in the face. Sans was  _livid._

“All right, I have had  _enough!_  You have ruined my kitchen, wasted my time, and harmed my brother!” Glaring about the kitchen, his voice was bordering on a screech as he demanded, “You  _will_  show yourself  _this instant!_ ”

“Hey, bro, maybe we should get Undyne to hel—”

A sudden scream pierced their skulls, causing them both to nearly crumple from the volume and intensity. Stars, that was an awful racket!

“ _What_  was  _that_  ghastly noise?!”

And another one sounded, much to their dismay. Papyrus tried to muffle the noise with his hood, grimacing. Was there something in the room with them?

“ _Stop that!_ ”

Yet another scream.

“ _Aaaaargh, I said STOP!_ ”

Great, now they were screaming at each other. Sans seemed determined to scream louder than their poltergeist.

…huh. Wait a second.

Papyrus took the opportunity to step out and gather some information, as his brother screamed out all of his frustrations.

By the time he’d returned, Sans had tired himself out completely, leaning against the table outside the kitchen. He glared at his brother for abandoning him, but Papyrus held up a hand. Despite Sans’ frustrations, he was curious about the look in his sockets. So, he watched from the doorway, as his brother started preparing himself a bowl of cereal.

Despite the earlier screaming match, there didn’t seem to be anything strange going on in the kitchen. Papyrus made his bowl without incident, and took it back out to eat at the table. It was… perplexing. Sans opened his mouth to ask what he was doing, but his brother lifted a finger, then motioned for him to enter the kitchen—miming a zipper across his grin.

…sure, fine, you know what? He wouldn’t give the intruder any satisfaction! So he marched in there, boots stomping across the tile, and put away Papyrus’ things. Almost immediately, the box fell over on its own. Sans merely picked it up and placed it back in the cabinet. When he turned away, he heard it open up again, but stubbornly ignored it.

Papyrus gave him a thumbs-up.

A bit more confident now, Sans strode over to the stove to prepare a pot of water. He gritted his teeth when pasta boxes started to fall off of the shelves—he wanted to clean it up immediately—but stuck to his guns. In fact, he scooped up the particular box of noodles he’d planned to make, leaving the rest where they lie.

After a bit of time, one of the boxes was pushed against his shoe. He barely glanced at it.

The fridge was opened, but Papyrus came in and closed it on his way to the sink. His bowl taken care of, he leaned against the counter beside his brother while the water boiled, looking rather smug.

“Y'know,” he suddenly broke the silence, “’s been a while since we had company over.”

Sans gave him a perplexed look. They didn’t…  _have_  any company? A soft noise in the opposite corner made him reconsider. He wouldn’t exactly call this “company,” though.

“Thing is, they normally call before bargin’ in,” Papyrus went on, hands sliding into his hoodie pockets. “That way we can treat ‘em proper.” He chuckled. “No one likes an uninvited guest.”

The cabinets swung slightly, as if there was a breeze in their kitchen. Sans squinted, wondering what his brother was playing at. Was he… trying to converse with this intruder? Why?

“Now, a li’l fishie told me, sometimes these spirit things, they have… unfinished business, yeah? So they stick around, cause some mayhem, 'til the people they’re harassin’ leave, go mad, or die.”

Playing with a toothpick, Papyrus teased at his teeth as he eyed the still swinging cabinet door.

“Got some news for ya, li’l “guest.” Me and my bro? We ain’t dyin’, 'n we’re pro'ly already pretty mad, considerin’ where we came from.” Grin sharp, he added, “'N we sure as hell ain’t leavin’ this place.”

Sans couldn’t help a snort. “Of course not! I am not being driven from my house by some wailing, invisible nuisance!” A faint moaning cry rung in the air, but a hand on his shoulder stopped him from continuing his tirade.

“Dunno what kinda business ya gotta finish, but right now, yer not gettin’ anywhere. I think we’re pretty agreeable monsters, willin’ to overlook transgressions 'n come to a truce. So how’s about ya stop lookin’ to rile us up, 'n cooperate, before we have t’ look into more… extreme measures.”

…all right, Sans wouldn’t admit this aloud to most, but he was glad that Papyrus was his brother, and also on his side for everything. Because the look on his face said that the alternative to cooperation would not be pretty, for the intruder. Whatever  _that_  might involve.

There was a bit more noise, and a few more flung items, but after a bit, much to their relief, it seemed to quiet down. Sans was able to finish his cooking in peace, and the items returned to their places remained there. And they didn’t wake up to a destroyed kitchen the next morning, though some of the cabinets were open again. Of course, that wouldn’t do, and so Papyrus found himself witness to an amusing sight: Sans trying to discipline and train a poltergeist in the arts of cooking.

“No, no, no, you must set the dial higher! We want the water to boil  _before tomorrow!_ ”

“ _Aaaaaaah!_ ”

“Don’t you wail at me! Do you doubt The Great Sans? I am a culinary master!”

“ _…ooooooh…_ ”

_Splash!_

Snorting, Papyrus couldn’t help pointing out, “I don’ think the pasta box’s s'posed to be boiled—”

“We are working our way up to opening the containers—and  _you_  could use the fiber for your backbone!” Sans’ attention was drawn to a shaker that toppled over on the counter. “ _No,_  we don’t want to add salt! Anymore, and we might as well call this sea-ghetti!”

“ _Aaaaeeeeh!_ ”

“Need I remind you  _who_  is wearing the chef’s hat?”

“ _…youuuuuu…_ ”

“That is correct, and you would do well to remember that! Once you are capable of  _properly handing me_  these ingredients, then perhaps you will be upgraded from minion to apprentice, and we can work on your dexterity!”

Maybe now his brother could have another way to blow off some steam, Papyrus thought. Eh, he could only hope. It was almost like having a house guest, like he’d mentioned before. Maybe they could get along well.

“ _Oooooogh…_ ”

“Don’t you use that tone of voice with me!”

…or well enough, at least. Sans looked about ready to throw a bone or two.


	2. Chapter 2

**Summary for the Chapter:**

> Living together for a time, inevitably you get curious. Also inevitably, you make mistakes.

 

Sans hadn't thought that their house would get another individual in it, let alone keep them... but he admitted, at least in his head, that he liked their once-uninvited guest.

They were strange, no doubt. They didn't speak in full sentences, or in many words at all. He had never seen them, only seen what they manipulated. Both of these factors made it more difficult to learn more about them, which frustrated him. How was he supposed to introduce them to anyone who visited? Or to describe them in conversations?

But, despite the inconveniences they caused, they also solved many others. He didn't worry about anyone breaking into their house anymore, after Alphys had come in unannounced and gotten assaulted. He wasn't too happy about the new dent in a rectangular pan, but he supposed it was better than getting blood on the carpet. He could always count on them to be conscious. They were also eager to help around the house, which was useful when his brother tried to leave messes or Sans wanted a kitchen helper.

Overall, the small Co-Captain of the Royal Guard could tolerate this guest. As long as they didn't cross into his bedroom, and continued to be helpful instead of a nuisance.

The former of these rules was broken in quite the unexpected way.

He didn't often remember his dreams, but he definitely remembered this one. It was one where he woke up in his room to find a glowing orb. Just... floating there. He tried batting it away, blowing on it, even using his greatest magic attack, but it wouldn't leave!

“You will exit my personal quarters,” he finally told it, voice low. “If you do not, I will be forced to eradicate you as the intruder you are.” It was the voice he used for those attempting to deny him the respect he deserved.

At last, the light flickered, and then vanished. In its place, was a small rabbit.

Sans stared at the rabbit.

The rabbit stared back.

When he lifted his arm, its ears flicked upwards. He paused mid-summoning. Had it squeaked?

“Please no!”

No, that wasn't a squeak.

“A talking rabbit,” he muttered. He hadn't had this dream in years. After all, adults don't read  _Peek-A-Boo With Fluffy Bunny_. His arm returned to its crossed position as he glared at it. “State your business, Fluffy Bunny.”

“Uh... well.” It would've been strange to see a storybook character come to life outside of a dream. There are rabbit monsters, yes, but only one Fluffy Bunny. Said bunny sat back on its hind legs in a rather uncomfortable pose. Was it trying to stand like him? “I wanted to... introduce myself.”

“I know who you are,” he cut in. “Fluffy Bunny, the main character of a children's storybook.” Did it think he was an idiot?

“Wha... no, no! That's because of your perceptions!” The way it waved its paws was amusing, in a way. Such a fragile creature trying to be so forceful. “I just didn't want to alarm you!”

“...very well, Not Fluffy Bunny, then who  _are_  you?”

“I... am the one who's been living with you two for a... a while.” It had to be referring to him and his brother. But of course, he hadn't housed a rabbit, monster or otherwise. The only individual it could be referring to is...

“You claim you are the invisible trespasser, who has made themselves at home here.”

The ears flicked up, then lied flat against its head. “I'm... still a trespasser?” It seemed to falter, looking rather upset for a rabbit.

Sans considered this. This was most definitely a dream, so he doubted any of this was real. But if it were, he disliked the thought of the banshee returning to their troublesome ways over a perceived insult.

“...perhaps not entirely. You have been quite the useful addition to our household.  _However,_ ” he continued when it perked up at the praise, “this does  _not_  grant you permission to break the house rules!”

“The—the rules?”

“You are  _in._  My  _room._ ”

The rabbit squeaked, then flung itself at his feet. “I'm sorry! But—but this was the only way I could figure out how to talk to either of you!” It quivered, careful not to actually touch him even now. He didn't really like watching his childhood hero curled at his feet.

So he grabbed it, holding it up by the scruff of its neck. “Then talk,” he commanded.

“A-ah, p... please, just... just put me down and I'll, I'll talk, I'll tell you whatever you want to know! Please,  _please—_ ”

_Thump._

Sans narrowed his eyes as the rabbit scurried out of arm's reach. Why were its little paws reaching for its neck? Surely it knew it couldn't properly grasp it. That at least proved whatever it was normally had a reasonable reach of its own. Perhaps it was a dead human? A ghost with limbs? Though the ghosts in the Underground have never had issues becoming visible. He would get his answers.

“What do you look like, when you aren't impersonating a storybook character?”

Finally giving up on its gesture, it had a good shake and started to clean one of its ears. “I don't look like... much of anything,” it admitted. Its gaze was elsewhere.  _That won't do._

“Yet you have influence on the physical plane.” The tap of his shoe brought its attention back to him. Him tapping a bone on his arm ensured that he kept it. “You  _must_  have a form behind it.”

Its nose twitched. It was not cute.

“It's... It's not really a physical form, like how you and your brother are. It's... I'm there. I exist. But, I also don't, exactly?” The bone tapped more loudly, and it cowered. “I-I... what I mean is—”

“How did you come across our home?”

“I found myself inside of it, and I—”

“What caused you to pester us?” When the rabbit clammed up, Sans pushed, “Why can't you always speak with me? Is barging into my dreams  _really_  the only way?”

The bombardment of questions had been too much. The rabbit had crouched lower and lower, until suddenly, it released an ear-splitting scream. He clutched his skull, despite not having ears, the high and shrill noise piercing like a rail spike. It sounded like a child's last cry for help.

Then a burst of light filled the room, blinding him. And he woke up, for real, sitting straight up in bed. The rabbit was not there, of course. Because it was a dream.

Nothing but a dream.

* * *

“Papyrus.”

“Yeah, bro?” The taller skeleton, leaning against the wall, cocked his head. “'Sup?” He could tell this was A Conversation.

Surprisingly, Sans didn't immediately dive into it. That is, there was a second of hesitation before he began, “Have you had any sleep at all?” It was enough of a pause to catch Papyrus' attention. Something had thrown his brother off-guard.

“Some, yeah. Why?”

“Good! You need proper rest every day, to be prepared for the next!” He tapped a bone on Papyrus' arm in warning, before folding his hands behind him again. The makeshift baton began a soft, steady tempo. “...now. Have you had any dreams?”

“I only dream 'f my great bro, o' course.” Papyrus accepted his punishment for teasing his brother, another  _whap_  of the baton. “Somethin' up? Been 'avin' bad dreams again?”

“Of course not. Don't be ridiculous.”

Yeah, there was something up. To be fair, Papyrus wasn't fibbing. He just wasn't going to tell him that his dream was of him having to eradicate his brother's doppelganger, when it tried to cajole him into something. The details were fuzzy... but he remembered a bright light, and something suddenly taking Sans' face for their own. The dream ended the moment after he disposed of them, and it didn't return the next night, so he had put it out of his mind.  _Hope he's not 'avin' THAT kinda dream._

“...anyway! Where is our hidden guest? I have a new recipe ready to concoct, but they haven't responded to my summons!”

“Y'mean, you shoutin' at them like yer maid,” Papyrus chuckled. “Yeah, wonder why.” Interesting subject change.

“Don't get smart with me! In fact,  _you_  are now my kitchen helper! Come along, brother!”

Shrugging, Papyrus fell into step behind him. “Eh. Suitable punishment.”

...it  _was_  kind of weird, though. Normally, the poltergeist would show signs of their presence: A counter cleaned with their designated rag, or another tally on the “Successful Dishes Washed By Guest” sticky note. Thinking back, Papyrus realized it had actually been a few days since he'd really been sure of their presence. Sure, it hadn't felt like they had up and vanished, but they also hadn't... really been  _present_ , either. But he didn't want to bring it up while Sans was busy cooking. He knew how his brother reacted to having his groove thrown off, especially with their “guest.” Neither had admitted it yet, but they kind of liked having them around.

_Hope they come back soon._

* * *

Sans was always punctual, in every aspect of his life. He woke up, left the house, came back, and fell asleep at the same time every day. There was a set schedule that he followed to the millisecond. Others could use him to set their clocks. He would prefer they do so, because he hated tardiness.

But could he call the poltergeist tardy if he had never confirmed an appointment with them? And if their only clock was the one in the house?

He was ten whole seconds late in falling asleep, scrutinizing his room for the seventh night in a row. Their guest had been quiet, only opening two cabinets and moving three utensils in that timespan, and he was hitting his limit.

“I demand you speak with me,” he said aloud to the room, before lying down to sleep proper. He really was a marvel.

Instead of his room or an inky abyss, Sans' dream took place in a large open field. Delicate flowers and soft grass spanned the distance to the horizon, with a circular clearing at the center where he stood. As he was again aware of his own slumber, he did not try to look around and find an explanation for his presence here.

He took a seat, cross-legged with hands braced on his knees, and closed his sockets.

And waited.

Eventually, he opened his eyes to find a glowing ball of light before him. Instead of snapping or threatening, he gave a short gesture, and waited some more. It took a bit of time... but eventually, the ball dissipated, and the rabbit had returned.

“...hi.”

What an anticlimactic greeting. His sockets narrowed for a moment.

“...you are the poltergeist, correct? Not Fluffy Bunny?”

It began cleaning its ears again, clearly nervous. “Yes... I am.”

“You have been avoiding us.”

“N-no, not... avoiding.” The longer he stared, the more the rabbit drooped. Finally, it turned its head and mumbled. “Not  _entirely..._  I, um... I only have so much energy, and this... this takes a lot out of me.”

“Then we only have so much time to speak like this,” Sans deduced.

When the rabbit... poltergeist... When the rabbit-geist nodded, he mirrored the gesture, before glancing down into his lap. A paper had appeared there, his own handwriting upon it.  _Bah, I don't need this!_  He had everything memorized.

But it caught their attention. “What is that?”

Begrudgingly, Sans flipped the paper around for them to see. They cautiously approached, until their beady eyes could read for themself what he had written there. “Guest... List?” Their head cocked, ears slanted to the side. It definitely wasn't cute.

“A list about my guest,” he corrected, earning their gaze on his face. “I know almost nothing about you. You haunt my home, you assist in chores, and you ward off intruders. That is all.”

The rabbit-geist looked back to the paper. Nose twitching. Then, they glanced at its paws.

“...um...”

Scoffing, Sans returned the list to his perspective, now clutching a pen.  _If only real life was this convenient._  He pointed it at the rabbit-geist. “I will fill it out. You will talk.”

They didn't seem too enthused, but they were definitely obligated to sit there with him and weather his interrogation. But with a proper list in mind and some time to mull this over, Sans did a much better job in pacing the questions to ensure efficiency. It went  _much_  better, thanks to that. His brother might poke fun at how meticulous and exacting he could be, but he couldn't deny that it streamlined many processes that would've been agony otherwise.

There might have been many things Sans couldn't learn about the rabbit-geist. Either they didn't know or couldn't remember (the exact nature of their being was still strange to them), or they were too uncomfortable to share for the time being.  _I hate not having all of the answers._

Despite this, it wasn't a total loss of a dream. Having it set in such a peaceful, quiet place let him enjoy the stretches of silence that spanned between them in between the tougher questions. Flowers had never held his attention for long, but the way they swayed in the distance, slowly becoming like waves on an earthy ocean...

Once the last line was filled, he rolled up the paper to watch it vanish. The contents would be ingrained into his memory, because he had never forgotten an important detail and he wasn't going to start now.

The rabbit-geist looked up at him, eyes a bit dull. Perhaps it truly  _did_  take a lot out of them.

“I have to leave soon,” they whispered, confirming this. Their head dipped once, as if exhausted, before their little furry forehead pressed against his knee.

Sans stilled.

They were barely audible, but he heard them anyway. “Can... can you stay with me... until the end?”

He stared, examining the vulnerable, softness of their borrowed form. Though he didn't agree to this, they took the lack of denial as confirmation—or they were simply too tired to move away. Glancing at the shifting flowers, dancing in a silent breeze, he chose to simply sit there until wakefulness returned to him.

Of course, he woke before sunlight had a chance to peek in through his window. It was the brightness of a full moon that trespassed instead, painting the walls of his bedroom. For a moment, he thought he saw something beside his bed.

It was gone before he finished sitting up.

Staring at the spot, Sans was nearly a minute late in preparing for his day. It was quite unlike him, but no one was witness to his lapse. So he was able to mull over their last words without interruption, the ones mumbled as if he wasn't there.

“ _...always hate... end comes too fast..”_

**Notes for the Chapter:**

> Another chapter for @enamoredfey! This one's prompt is "Mutt and Black's supernatural guest gets more comfortable around them, maybe entering dreams to talk to them/share about themself."

**Author's Note:**

> Written for @enamoredfey on tumblr, using the prompt "Mutt and Black deal with a banshee or some sort of ghost haunting their home." Thanks for the idea, lovely!
> 
> If you want to put in a request for more of this (or with different characters), or for something new, throw an ask at my writing blog, @thatdragonsdrabbles, a message here, or hit me up on Discord in my new server!
> 
> Discord server link: https://discord.gg/tKjpuQb


End file.
